1. Field of the Invention
This invention relates to a capacitor. More particularly, the invention relates to a capacitor which can have an increased capacity by the increase in capacitor effective area and a production method thereof. This capacitor is assembled into a semiconductor package or a wiring substrate or can be used as a single electronic component.
2. Description of the Related Art
A capacitor fabricated and built in a semiconductor device package or a wiring substrate is described in JP 11-68319 A, for example. A capacitor assembled as an electronic component into a semiconductor device package is described in JP 2001-274034 A, for example.
The capacitors of the prior art disclosed in JP 11-68319 A and JP 2001-274034 A are of a parallel flat sheet type in which a dielectric film is sandwiched between an upper electrode layer and a lower electrode layer. FIG. 12 schematically shows such a parallel flat sheet type capacitor. The capacitor shown in the drawing is made up of a lower electrode 204, a dielectric film 206 and an upper electrode 208 that are serially formed on an insulating material layer 202. The lower electrode 204 and the upper electrode 208 are respectively connected to wiring lines 216 and 218 for connecting the capacitor to other circuit components through connection terminals 212 and 214 that penetrate through an insulating layer 210 covering the capacitor. A protective film (insulating material film) 220 is disposed on the wiring lines 216 and 218.
As shown in FIG. 12, the parallel flat sheet type capacitor employs a construction in which the connection terminals 212 and 214 for connecting the capacitor to other circuit components are taken out from the lower electrode 204 and the upper electrode 208, respectively. In such a construction, the wiring line must be extended from the end of each electrode 204, 208 to a connection portion with each connection terminal 212, 214 and a resistance component and an inductance component accordingly become unavoidably large. Because the shapes of the upper and lower electrodes 208 and 204 are asymmetric, stable capacitor characteristics cannot be obtained easily, especially when the capacitor is used while connected to a radio frequency power source such as in the case of a capacitor built in a package substrate for mounting an LSI. Furthermore, a planar area (effective area) of the portion for forming the capacitor is limited and an increase in the capacity is therefore limited.